Rotary impact hand tool



March 13, 195! o. E. SZEKELY 2,544,736

ROTARY IMPACT HAND TOOL Filed May 25, 1945 INVENTOR.

OTTO E. SZEKELY ATTORNEY Patented Mar. 13, 1951 ROTARY IMPACT HAND TQOL Otto E. Szekely, United States Navy Application May 23, 1945, Serial No. 595,3

1 Claim.

This invention relates to new and useful improvements in hand tools and the like, and more particularly to hand tools for inserting and removing fastening devices such as screws, bolts and the like. 7.

When removing screws, bolts and like fasten- (cl. 8152.3) (Granted under the act of March a, 1883, as

ing devices by the use of screw-drivers, wrenches and like hand tools, considerable difficulty often is encountered in intially freeing the screw or .bolt from the object in which it is inserted, and in some cases, for example where the screw or bolt has become rusted or otherwise frozen to the object, it is quite often impossible to free the screw or bolt by the use of such a handtool,

. thereby causing delay and loss of valuable working time.

With the foregoing in mind, the principal object of the present invention is to provide a hand tool for screws, bolts and like fasteners .which embodies novel features of construction and arrangement operable to intially free and loosen such a fastener that is too tightly secured in or frozen to the object to be withdrawn therefrom by conventional hand tools employed in the usual manner.

- the object in which inserted so that such fastener may be withdrawn'in the conventional manner 7 by the tool, or in the opposite direction so that such a fastener may be tightened and secured in an object to a substantially greater degree than is possible by the use of hand tools employed in the customary manner.

A further object of the invention is to provide a novel hand tool having the characteristics and I features described which is of relatively simpli- -fied construction, comparatively inexpensive to manufacture and highly eflicient in use.

These and other objects of the invention and the various features and details of the construction and operation thereof are hereinafter fully set forth and described with reference to the accompanyin drawing; in which:

Fig. l is an elevational view of a hand tool embodying the present invention.

Fig. 2 is an enlarged sectional view vertically through the hand tool shown in Fig. 1; and

' Fig. 3 is a diagrammatic view illustrating a particular feature of the construction and operation of a hand tool made according to the invention.

Referring now to the drawing, and particularly to Figs. 1 and 2 theta;

amended April so. 1928; 370 0'. G. 757)] a hand tool made according to the present invention may comprise an open ended tubular casing structure I having on the exterior thereof a knurled or otherwise friction surfaced hand-grip portion 2. The upper end of the casing l, with reference to the drawing, is provided with a suitable closure cap 3 having a portion 4 thereof threaded internally of said casing, and-secured by means of a set screw or like fastening device 5. The other or lower end of the casing I has threaded externally thereon an annular'cap member 6 which is provided with an inturned flange portion 1, and the construction andarrangement of said cap memher 6 is such that when the latter is screwed tightly on to the lower-end of the casing Ii the inturned flange 1 thereof is" predeterminedly spaced outwardly fromthe adjacent end face of the casing-l. For a purpose hereinafter'described the exterior upper end portion of the casing may be provided-with a hexagonal or other polygonal shape as indicated at 8. V

Mounted for rotation within the casing I in the lower end portion thereof is a cylindrical driver member 9 having a radial flange portion In of greater diameter that is adapted to be received and retained in the previously mentioned space provided between the lower end face of the casing l and the inturned flange portion 1 of the annular cap member 6. It is to be noted that the spacing of the flange of cap member 6 fromthe adjacent end face of the casing I is such that the flange ID of the driver member 9 is received therein so as to permit relative rotation of the casing l with respect to member. 9 under circumstances and conditions hereinafter more fully described. 7

Projecting-coaxially endwise from the member 9 and outwardly through the opening defined by the annular cap member '6 is a lug or shank H. .This lug or shank II is constructed or arranged to detachably and interchangeably receive thereon the socket portion of a tool element such as, for example, a screwdriver l2, or of a socket type wrench element (not shown). Preferably the shank H is provided with a conventional ball and spring snap I 3 for engagement with a detent in the socket portion. of the selected tool element so as to detachably retain the latter thereon.

Also mounted for relative movement rotationally and axially within the casing l is a cylindrical hammer member l4. According to the present invention the adjacent end faces of the hammer member 1 4 and the driver member 9 are provided; respectively, with correspondingly shaped projecting cam portions I and I6 that are relatively tapered in a direction circumferentially of said members I4 and 9 so that their side faces are angularly disposed and arranged for cooperative interengagement with one another in the relationship shown in Fig. 2 of the drawing.

In the illustrated embodiment of the invention the hammer member I4 is provided with two such cam portions I5 and these are arranged in diametrically spaced relation circumferentially of the end face of said member I 4. On theother hand, the driver member 9 has four such cam portions I 6 arranged circumierentially of the end face thereof and spaced substantially '90 apart. The angular disposition of the side faces of both sets of the cam portions l5 and I 6, and the di- 4 ponent is built up in the spring I! by reason of the turning force manually applied to the casing I against the resistance to rotation of hammer member M afforded by the spring and the relatively inter-engaging projections I5 and it of the members It and 9, respectively and, as hammer member #4 continues to move rotationally relamensions and shape thereof, are substantially the 7 same and such that the cam portions I5 and I6 nicely interfit in the relation shown.

Positioned coaxially within the upper portion of the casing I is a relatively stiff coil spring 'I'I. One end of the spring I! is anchored to the adjacent end face of the hammer member I4, for

' example, by providing therein a groove I8 for reception of theadjacent end portion IQ of said spring, and the other end of the spring I? may ing I by means of a guide pin or like'element 22 I extending axially therein.

The construction and arrangement of the spring I1, and the stiffness thereof, are such that in normal use and operation of the tool to insert and withdraw a screw or bolt fastener, the said spring I! maintains the cam portions I5 and I5 of the members I4 and 9, respectively, in the relal tively interfitting or engaged position shown in Fig. 2 of the drawing, and prevents relative rotation between the hammer member I4 and the member 9.

However, when using the tool, for example, to

withdraw a screw or bolt fastener from an obiect in the customary manner of using such hand tools, should the driver member 9 be restrained or prevented from rotating with the remainder of the tool by reason of engagement of the tool element with a threaded fastener that is too tightly secured in or frozen" to the object to be I withdrawn therefrom by the maximum turning force that is capable of being applied manually to the tool, the spring I! is not too stiff to prevent a person using the tool from. applying suflicient turning force manually to the casing I to turn the latter in the indicated direction thereby tending H of the spring I1.

to twist spring IT which is sufficiently stiff to carry with it the hammer member I4 which rotates in the same direction relatively with respect to the member 9 that is restrained or held against rotation as previously described.

Relative rotation of the hammer member I4 with respect to the T member 9 causes the cam portions E5 on the hammer element M to ride upwardly or outwardly upon the adjacent cam portions I6 of the stationary member 9, as indicated at A in Fig. 3 of the drawing, thus producing a relative axial separation of the hammer member I4 with respect to the member 9 and effecting an axial compression Simultaneously a substantial twist force com tive to the member 9, the cam portions 15 thereof continue to ride upwardly or outwardly upon the portions I6 of the member 9, as indicated at B in Fig. 3, thereby progressively increasing the twist and compression forces in the spring IT. This action continues with relative rotation of the hammer member I4 until these twist and compression forces reach a maximum as the peaks of the cam portions I5 ride onto the peaks of the cam portions i6 of'the member 9. As the peaks of the cam portions it clear the peaks of the cam portions i5v the substantial twist and compression forces built up and stored in the spring ii are released instantaneously thereby thrusting the hammer member Hi downwardly substantially in the direction of the resultant of the lateral twist and axial compression forces in the sprin III with the result that the angular faces of the cam'portions l5 of the hammer memher It are caused to impinge upon the angular sion forces in the spring !'I, as shown at 'C' in Fig} 3, thereby imparting to the driver member 9 hammerlike blows which are transmitted thereby through th etool element to the frozen fastener thus serving to unfreeze and loosen the latter to permit it to be withdrawn from the object in the usual manner by the hand tool.'

It will be obvious, of course, that as many hammerlike blows as required or desired may be imparted to the driver member 9 in the manner described by the application of suflicient turning force to the tool casing I to effect continued relative rotation thereof and of the hammer memher I4 with respect to the driver member 9 which is restrained or held against rotation and, as previously stated, the exterior upper end portion of the casing] may be hexagonally or otherwise shaped as-indicated at 8 to receive a suitable ner to wrench or like device to provide leverage for the application of forces suflicient to loosen and withdraw threaded bolt type fasteners by the use of a socket wrench type of tool element (not shown) applied to the shank II of the tool as previously described.

It will be apparent that a hand tool constructed and arranged as herein described also may be employed and operated in a similar manimpart sharp, hammerlike blows to threaded fasteners being inserted into an object so that the same may be tightened and secured therein to a substantially greater degree than is possible by the use of conventional hand tools employed in the customary manner. In this event the rotational movements of the casing I and hammer member I4 will take place in a direction opposite that indicated by the arrows in Fig. 2, and the direction of movement of the cam portions I5 of the hammer member It relative to the cam portions l6 of the driver member will be in a leftward direction with reference to Fig. 3 rather than toward the right as there illustrated.

From the foregoing it will be observed that the present invention provides a novel hand tool for screws, bolts and like threaded fasteners which may be operated effectively both to initially free or loosen threaded fasteners that are too tightly secured in or frozen to the object so that they cannot be withdrawn by conventional hand tools employed in the customary manner, and to secure a threaded fastener in an object to a considerably tighter degree than is otherwise possible with conventional hand tools. The invention also provides a novel hand tool of the stated character having means operable toimpart a succession of sharp, hammerlike blows to a fastener either to free and loosen the same initially with respect to the object in which inserted, or to tighten the same therein. The invention further provides a novel hand tool having the characteristics and features described which is of relatively simple construction, comparatively inexpensive to manufacture, and which is fool-proof and efficient in use.

While a particular embodiment of the present invention has been illustrated and described therein, it is not intended to limit the invention to such disclosure, and it is contemplated that changes and modifications therein and thereto, as well as in the general form and design of the tool, may be made within the scope of the claims.

The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

I claim:

In a hand tool for imparting rotational movement in either direction to threaded fasteners, a casing providing a hand grip and adapted to be rotated about its axis, a driver member in said casing extending from one end thereof, a hammer member rotationally and axially movable within said casing, a plurality of cooperatively engaged rounded sawtooth shaped cam portions on the adjacent circumferential end faces of said driver and hammer members, and a spring within said casing secured thereto by one end and secured by the other end to said hammer member, said spring operable to resiliently restrain movement axially and rotationally of said hammer member relative to said casing and thereby to transmit rotational movement of said casing through the engaged cam'portions to said driver member until external restraint of rotational movement of said driver member restrains cooperative movement of said hammer member and applies torsional force to said spring whereupon said spring is distorted and compressed to the extent that the engaged cam portions disengage and reengage upon succeeding cam portions to impart rotational blows on said driver member dueto the rotational force momentarily stored in said spring.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Livermont Apr. 20, 1948 OTTO E. SZEKELY. I 

